The present invention relates to an improvement in a vehicle floor structure.
A vehicle floor is a floor panel provided in the midsection of a body frame, to face a vehicle compartment. A floor panel has a front floor panel and a rear floor panel. A floor panel generally consists of one or two press-molded steel plates. To ensure required rigidity, a structure of reinforcing it with a floor frame is therefore used.
In recent years, studies to increase the rigidity of the floor panel have proceeded. As such an art of the vehicle floor structure, Japanese Patent Laid-Open Publication No. HEI-10-338170 xe2x80x9cMethod of Mounting Honeycomb Plate to Vehicle Floorxe2x80x9d is known, for example.
The above conventional art provides a structure in which fixing melting sheets are laid on the bottom surfaces of a plurality of recesses formed on a floor panel, into which recesses honeycomb plates are fitted from above, and flat substrates integrally provided on the top surfaces of the honeycomb plates are fixed to the brims of the recesses. The rigidity of the floor panel is increased by the honeycomb plates.
Although being able to partially increase the rigidity of the floor panel, the above conventional art does not entirely increase the rigidity of the floor panel. It is thus necessary to reinforce the floor panel with reinforcing members such as a plurality of front crossmembers and a plurality of rear crossmembers. In order to increase the degree of freedom in the layout of attachments (such as an exhaust system) to a vehicle body, it is preferable to reduce the number of reinforcing members. Thus desired is a floor structure being able to entirely increase the rigidity of a floor panel without being provided with a floor frame for reinforcing the floor panel and to efficiently absorb impact energy when an impact force acts on the floor panel.
According to the present invention, there is provided a vehicle floor structure, which comprises: a body frame; and a floor body of a hollow panel having a first flat plate, a plurality of core materials arranged with spaces on the first flat plate, and a second flat plate placed over the core materials; wherein, core materials in edge portions of the floor body are joined to the body frame.
The use of a hollow panel integrally formed by spacing a plurality of core materials on a flat plate and placing another flat plate thereover, as a floor body, can increase the rigidity and strength of the entire floor against bending, torsion and shearing. Furthermore, joining core materials in edge portions of the floor body to a body frame further increase the rigidity of the entire floor body. The entire floor body is thus increased in rigidity without being provided with a floor frame consisting of additional members for reinforcing the floor body. The elimination of a floor frame can further increase the degree of freedom in the layout of attachments (such as an exhaust system) to the vehicle body.
Impact forces acting through the body frame on the floor body are efficiently dispersed all over the floor body with the core materials spaced from one another between the upper and lower flat plates, so that the floor body as a whole can sufficiently absorb impact energy. The floor body has an increased efficiency in impact energy absorption.
The dispersion of impact forces with the core materials prevents the concentration of excessive stress on a part of the floor body.
The arrangement of the core materials largely increases the strength of the upper and lower flat plates against buckling, increasing the proof stress of the floor body and the vehicle compartment (cabin), increasing the amount of deformation of side frames, and resulting in an increased energy absorption efficiency.
The use of the hollow panel as the floor body and the arrangement of the core materials in the floor body increase equally the surface rigidity of the floor body and eliminate any locally-greatly-vibrating area. The vibration of the floor body can thus be further reduced.
According to the present invention, there is further provided a vehicle floor structure, which comprises; left and right front side frames extending rearward from the vehicle front; and a floor body of a hollow panel having a first flat plate, a plurality of core materials arranged with spaces on the first flat plate, and a second flat plate placed over the core materials; wherein, the front of the floor body is connected to the rear ends of the left and right front side frames, and the core materials in a front edge portion of the floor body are arranged to extend radially rearward directly or indirectly from the rear ends of the left and right front side frames.
The use of a hollow panel integrally formed by spacing a plurality of core materials on a flat plate and placing another flat plate thereover, as a floor body, can increase the rigidity and strength of the entire floor against bending, torsion and shearing. Furthermore, joining core materials in edge portions of the floor body to a body frame further increase the rigidity of the entire floor body. The entire floor body is thus increased in rigidity without being provided with a floor frame consisting of additional members for reinforcing the floor body. The elimination of a floor frame can further increase the degree of freedom in the layout of attachments (such as an exhaust system) to the vehicle body.
Arranging core materials in a front edge portion of the floor body to extend radially rearward directly or indirectly from the rear ends of the left and right front side frames allows an impact force from forward of the vehicle body to be efficiently dispersed all over the floor body. The floor body as a whole can thus sufficiently absorb impact energy. The floor body has an increased efficiency in impact energy absorption.
In the present invention, the core materials preferably include a plurality of longitudinal core materials extending longitudinally and arranged side by side in the vehicle transverse direction, and, among the longitudinal core materials, the arrangement pitch of longitudinal core materials substantially corresponding to the rear ends of the left and right front side frames is set smaller than the arrangement pitch of the other longitudinal core materials.
That is, the strength of only the longitudinal core materials substantially corresponding to the rear ends of the front side frames is increased and the strength of the other longitudinal cores is left unchanged. Balanced setting of the respective strengths of the longitudinal core materials with a limited increase in weight of the floor body can increase the strength of the entire floor body against an impact force from forward of the vehicle body acting through the left and front side frames on the front of the floor body.
Further, in the present invention, the core materials are preferably formed by bending plate materials, and, among the bent plate materials, the plate thickness of bent plate materials extending longitudinally, substantially corresponding to the rear ends of the left and right front side frames, is set larger than the plate thickness of the other bent plate materials.
That is, the plate thickness of only the bent plate materials substantially corresponding to the rear ends of the front side frames is set larger to further increase the strength of the bent plate materials. The strength of the other longitudinal core materials is left unchanged. Balanced setting of the respective strengths of the longitudinal core materials with a limited increase in weight of the floor body can increase the strength of the entire floor body against an impact force from forward of the vehicle body acting through the left and front side frames on the front of the floor body.